Travel rails for suspended crabs are made from roll-formed sheet steel for cost and weight reasons. One example of such a travel rail is described in DE 41 19 868 A1. The rail forms a hollow bottom flange and a hollow top flange that are connected to one another by a web. The web is configured as a single piece with one-half of the hollow top flange and one-half of the hollow bottom flange situated thereunder. The other halves of the top flange and the bottom flange consist of two individual roll-formed sheets that are then correctly positioned and joined to the part containing the web. These parts are then welded together.
The welding costs are relatively high since, during the welding process, the parts must be correctly positioned and fixed in place by means of corresponding devices. Furthermore, the welding seams are located where there is a risk of welding distortions. It is particularly difficult to produce long, reliable MAG welding seams on relatively thin material. Due to its shape, the rail is also susceptible to bending during transport and has a low torsional rigidity.